Role of soil organic matter in urea adsorption

Oxidation of organic matter by peroxidation or ignition resulted in considerable decrease in urea adsorption (Kd) by soils; the effect was more pronounced in organic than in mineral soils. Peroxidation was more effective than ignition in reducing Kd values, even though ignition resulted in total loss of organic matter. Attempts were made to assess the effects of sequential removal of lipids, resins water-soluble polysaccharides, polyuronides, humic and fulvic acids on the urea adsorption process. The latter two fractions were the most important in the process.